OFFSET
1,2
LINKS
EXAMPLE
The initial coefficients of successive iterations of g.f. A(x) = x/(1 - x)^3 are as follows:
n = 1: 0, (1), 3, 6, 10, 15, ... g.f. A(x)
n = 2: 0, 1, (6), 30, 137, 588, ... g.f. A(A(x))
n = 3: 0, 1, 9, (72), 543, 3933, ... g.f. A(A(A(x)))
n = 4: 0, 1, 12, 132, (1390), 14208, ... g.f. A(A(A(A(x))))
n = 5: 0, 1, 15, 210, 2840, (37515), ... g.f. A(A(A(A(A(x)))))
MATHEMATICA
Table[SeriesCoefficient[Nest[Function[x, x/(1 - x)^3], x, n], {x, 0, n}], {n, 18}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Apr 06 2018
STATUS
approved